Doug fir is weeping
Weeping out of a Douglas-fir is commonly the tree responding to an insect or disease concern, but that doesn't mean the tree is unhealthy over all. Sap flow from the trunk can be caused by heart rot fungi, or root rot fungi when it is near the base. This can be a more serious problem over the long term as it affects overall tree health and also the risk of tree failure (breakage, or falling over) due to rotten wood. It is often exacerbated by drought because depending on the extensiveness of the rot it can inhibit water from getting to the top of the tree. If it is a rot then it sounds like it may not be too far along especially if you aren't noticing any discoloration or thinning of the crown of the tree. If you notice the overall health of the tree fade, then a hazard tree evaluation by an arborist may be called for if the tree is near your home.
Bark beetle attacks also cause sap flow, usually many small streams from many individual beetle attacks. This picture shows the sap more concentrated in one spot which may indicate it isn't a beetle. That being said, healthy trees can "pitch out" a small number of bark beetles and not be seriously affected. Trees stressed by drought or other issues can attract beetle attacks and be overcome if a large number of beetles attach at once. The picture does not show signs of this in your photo, but it is something you could watch for. Note if other sap streams show up, or if there are small holes with sawdust near around the base of the tree.